KR101739648B1

KR101739648B1 - Multi-leaf collimator

Info

Publication number: KR101739648B1
Application number: KR1020150126593A
Authority: KR
Inventors: 김정인; 민철희; 박종민; 성원모; 정성문
Original assignee: 서울대학교병원
Priority date: 2015-09-07
Filing date: 2015-09-07
Publication date: 2017-05-24
Also published as: WO2017043783A1; KR20170029348A

Abstract

The present invention relates to a multileaf collimator for use in radiation therapy, wherein the multileaf collimator according to an embodiment of the present invention comprises a pair of leaf assemblies. The leaf assemblies of the multi-leaf collimator each have a plurality of leaves and are arranged to face each other, and the leaves of the leaf assemblies are movable in a first direction in which the leaf assemblies face each other while being perpendicular to the first direction, And is also movable in the second direction.

Description

Multilayer Collimator {MULTI-LEAF COLLIMATOR}

The present invention relates to a multileaf collimator for use in radiation therapy, and more particularly, to a multileaf collimator capable of simultaneously operating in a two-dimensional direction.

Radiation therapy is one of the three major cancer treatment methods in addition to surgery and chemotherapy, and is a treatment method of killing cancer cells by irradiating tumor volume. Generally, radiotherapy is performed by examining the tumor volume and normal organs from the body image obtained by X-ray and CT, and then calculating the radiation dose to be the target tumor volume, The treatment proceeds.

In radiation therapy, it is important to minimize radiation transmission to the normal organs around the tumor volume, while at the same time delivering enough radiation to kill cancer cells in the tumor volume.

1A and 1B are views showing a conventional two-dimensional radiation treatment method and a three-dimensional stereolithography type radiation treatment method, respectively. First, referring to FIG. 1A, in a conventional two-dimensional radiotherapy, a two-dimensional image obtained through X-ray imaging is read to determine the position and size of a tumor volume, and then a radiation treatment region is calculated based on the position and size of the tumor volume . However, in the two-dimensional radiotherapy method, not only the tumor volume but also the surrounding normal organ is irradiated with a high radiation dose.

In order to solve the problem of the two-dimensional radiotherapy method, as shown in FIG. 1B, a three-dimensional body image is obtained through a CT scan, and a complex three-dimensional radiation irradiation plan The three-dimensional stereotactic therapy system was introduced. However, even in the case of 3D stereotactic radiotherapy, a small amount of radiation is applied to the surrounding normal organ, rather than the two-dimensional radiotherapy, and in order to establish the treatment plan, that is, There is a problem that a lot of time and manpower are consumed.

Recently, in order to treat the tumor volume more precisely than 2D radiotherapy and 3D stereotactic radiotherapy, intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT) therapy has been used. Intensity modulated radiotherapy is a treatment modality in which the intensity of radiation is spatially modulated to deliver sufficient radiation dose to the tumor volume and to minimize exposure to normal organs. Volume modulated radiation therapy, A multi-leaf collimator (MLC) is mainly used for the spatial modulation of radiation intensity in these treatment modalities, in which a gantry equipped with an irradiation device is rotated to transmit radiation more precisely.

Fig. 2 is a view showing an existing multi-leaf collimator. In the conventional multi-leaf collimator 10, a plurality of sets of two leaves 11 are arranged facing each other. The leaf 11 serves to shield the radiation, and the radiation irradiated toward the multi-collimator 10 passes through a space (opening) formed between the leaves 11. [ That is, the multi-collimator controls the intensity of the radiation by selectively shielding the radiation emitted in a specific direction.

On the other hand, in order to perform precise treatment in intensity-modulated radiation therapy and volume-modulated radiation therapy using a multileaf collimator, the spatial resolution of the radiation distribution through the multi-collimator should be excellent. That is, the distance (space) at which the radiation irradiated toward the target can be distinguished from the adjacent radiation should be made small so that the desired amount of radiation can be irradiated to the desired region.

Many studies have been carried out to improve the resolution of radiation distribution in multi-leaf collimators. Many studies have shown that the leaf thickness of the multi-leaf collimator is related to the spatial resolution of the radiation distribution and the spatial resolution is improved by thinning the leaf thickness. Is known.

However, there are physical limitations in reducing the thickness of the leaf, which limits the improvement in resolution. If the same total irradiation area is created by a multi-leaf collimator, the smaller the thickness of the leaf, the more leaves are needed, and the system for operating the leaf needs to be increased accordingly. Also, there is a problem that as the leaf thickness becomes thinner, the amount of radiation leaking into the space between the leaves increases.

As described above, it is difficult to obtain the desired spatial resolution only by controlling the leaf thickness of the multi-leaf collimator. Therefore, another approach is needed to improve the resolution of the radiation distribution.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a multi-collimator capable of improving the resolution of a radiation distribution map so that the radiation dose to the normal organ is minimized The purpose of that is to do.

A multi-leaf collimator according to an embodiment of the present invention includes a pair of leaf assemblies. The leaf assemblies each having a plurality of leaves and arranged to face each other, the leaves of the leaf assemblies being movable in a first direction in which the leaf assemblies face each other and in a second direction As shown in FIG.

The movement of the leaf of the leaf assembly in the first direction may be accomplished by driving a motor individually connected to each of the plurality of leaves.

The multi-leaf collimator according to an embodiment of the present invention may further include a guide rail, a motor for driving the guide rail, and a connection portion connecting the guide rail and the leaf assembly. The movement of the leaf of the leaf assembly in the second direction, Can be accomplished by operation of the rails.

The movement of the leaf of the leaf assembly in the second direction may be in a range less than the thickness of the leaf measured along the second direction.

The movement of the leaf of the leaf assembly in the second direction can be done in such a way that the plurality of leaves move equally throughout.

According to the embodiment of the present invention, the resolution of the radiation distribution can be improved by configuring the leaf of the multi-collimator to be movable in two directions orthogonal to each other. Accordingly, the amount of radiation irradiated to the normal organ can be minimized while delivering a radiation dose exactly to the tumor volume during the radiation treatment, and thus it is possible to treat the patient who can not perform the surgical operation through the radiation treatment .

1A and 1B are views showing a conventional two-dimensional radiation treatment method and a three-dimensional stereolithography type radiation treatment method, respectively.
2 is a schematic view of a conventional multi-lobe collimator.
3 is a schematic view of a radiation irradiation system using a multi-lobe collimator according to an embodiment of the present invention.
FIG. 4 is a view illustrating a multicolor collimator according to an exemplary embodiment of the present invention.
5 is a view illustrating a leaf of a multi-color collimator according to an embodiment of the present invention.
FIGS. 6A and 6B are diagrams showing a distribution of radiation intensity and a region to which radiation is transmitted when the conventional multi-color collimator and the collimator according to the embodiment of the present invention irradiate the radiation. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In order to clearly illustrate the present invention, parts that are not related to the present invention are omitted, and the same components are denoted by the same reference numerals throughout the specification. The sizes and the like of the respective components shown in the drawings are arbitrarily shown for convenience of explanation, and the present invention is not necessarily limited to those shown in the drawings.

That is, the specific shapes, structures, and characteristics described in the specification can be implemented by changing from one embodiment to another embodiment without departing from the spirit and scope of the present invention. It is to be understood that changes may be made without departing from the scope. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention should be construed as encompassing the scope of the appended claims and all equivalents thereof.

3 is a schematic view of a radiation irradiation system using a multi-collimator according to an embodiment of the present invention. The radiation irradiation system includes a radiation source 100, a first collimator 200, and a second collimator 300 , These components being mounted and supported in a device such as, for example, a gantry.

Referring to FIG. 3, the radiation generated by the radiation source 100 passes through the first collimator 200 and the second collimator 300 and is irradiated to the target 400. As the radiation source 100, radiation or radioactive isotope (for example, Co-60) generated in the linear accelerator may be used, but the present invention is not limited thereto and other sources may be used.

The irradiation area and intensity of the radiation generated in the radiation source 100 are controlled through the first collimator 200 and the second collimator 300. The first collimator 200 defines an area where the radiation generated by the radiation source 100 passes and which is disposed adjacent to the radiation source 100. The second collimator 300 defines a region where the radiation is irradiated from the target 400 And the radiation dose to be irradiated for each area, that is, the radiation intensity is determined.

The irradiation system may further include other components in addition to these collimators. For example, it may comprise one or more sets of jaws that are movable in the x-direction or the y-direction to form a rectangular shaped beam.

In order to perform precise treatment at the time of performing intensity-modulated radiation therapy or volumetric modulated radiation therapy using such a radiation irradiation system, the spatial resolution of the radiation distribution pattern should be excellent. Accordingly, in this embodiment, the second collimator 300, which sets the irradiation area and determines the radiation intensity, is formed of a specific type of multi-collimator.

According to the previous studies, it is known that the spatial resolution of the radiation distribution can be improved by thinning the leaf thickness of the multi-leaf collimator. Currently, a multi-leaf collimator using a leaf having a thickness of about 1.6 mm is known. However, there are physical limitations in continuously reducing leaf thickness. Furthermore, when the number of leaves is increased while reducing the thickness of the leaf, a driving system for each leaf is additionally required, and radiation leakage between the leaves also increases. An increase in the amount of leakage radiation can lead to unexpected secondary cancer development due to radiation exposure to the normal organ.

On the other hand, studies have been conducted to improve the accuracy of radiation therapy while tracking the actual tumor movement in real time. However, in order to track the movement of the tumor in real time, there is no effect on the spatial resolution of the radiation distribution even when the gantry equipped with the multi-collimator is rotated. In this case, the x- The radiation dose may be increased.

The present inventors have studied a new approach to improve the spatial resolution because of the limitations in improving the spatial resolution of the radiation distribution map according to the existing studies. Accordingly, the present inventors have studied a new approach to improve the spatial resolution, The spatial resolution of the radiation distribution is significantly improved when the radiation is irradiated while simultaneously moving in the x- and y-directions.

Accordingly, in order to improve the spatial resolution of the radiation distribution, the present invention is configured so that the leaves of the multi-leaf collimator can be moved in a two-dimensional direction instead of only moving in a one-dimensional direction. Hereinafter, the configuration of a multicolor collimator according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 4 is a view showing a multilayer collimator according to the present embodiment, and FIG. 5 is a view showing one leaf in the multilayer collimator according to the present embodiment.

4, a pair of leaf assemblies 310 including a plurality of leaves 311 and disposed to face each other are installed at the center of the multi-leaf collimator 300 according to the present embodiment. The individual leaf 311 of the leaf assembly 310 is formed of a material capable of shielding radiation, for example, tungsten, carbon steel, or the like, and serves to shield radiation irradiated toward the target.

The plurality of leaves 311 have the same shape and are configured to be individually movable in a first direction (the x-direction in Fig. 3 and the lateral direction in Fig. 4), so that the radiation passes through the multi-collimator 300 And control the intensity and the intensity of the area.

5, a protrusion 311a is formed on one side of the leaf 311 according to the present embodiment along the longitudinal direction, that is, the y-direction in FIG. 5, And the protrusions 311a and the concave portions 311b are formed to match with each other.

The plurality of leaves 311 are arranged side by side along the thickness direction, that is, the x-direction in Fig. 5, as shown in Fig. 4. Specifically, the projections of one leaf are aligned with the recesses of the leaves adjacent thereto, Are arranged in such a manner as to match the protrusions adjacent thereto.

The protrusion 311a of the leaf 311 is in contact with the concave portion of the leaf adjacent to the leaf 311 and the concave portion 311b of the leaf 311 is in contact with the concave portion of the leaf And is moved in such a manner that it slides on the projecting portion of the leaf adjacent thereto. The movement in the longitudinal direction (y-direction) of the leaf 311 can be done by a motor (not shown) connected to the individual leaf 311. However, the shape and driving manner of the leaf is not limited to this, and the shape of the individual leaf and its driving can also be realized by other known methods.

4, the multicolor collimator 300 according to the present embodiment includes a carriage 320 installed on both sides of the leaf assembly 310 and a carriage 320 connected to the leaf assembly 310 to move the leaf assembly 310 A rail assembly 330 is installed.

The rail assembly 330 includes a guide rail 331, a motor 333 for driving the guide rail 331 and a connecting portion 335 for connecting the guide rail 331 and the leaf assembly 310.

3 and 5, the guide rail 331 is disposed in the second direction orthogonal to the first direction in which the individual leaf 311 is moved by the drive of the motor 333, that is, the thickness direction of the leaf 311, The leaf assembly 310 connected to the guide rail 331 through the connection portion 335 can also be moved in the second direction.

The rail assembly 330 can be installed in each of the carriages 320 adjacent to the pair of leaf assemblies 310. The guide rails 331 and the motors 333 are driven by the pair of leaves The assemblies 310 may each move in a second direction. At this time, the movement of the leaf assembly 310 in the second direction by the rail assembly 330 can be set to be smaller than the thickness of the individual leaf 311.

The multi-leaf collimator of this embodiment can be connected to a control unit (not shown) that controls the movement of the leaf assembly. The controller controls the movement amount of the leaf assembly and the movement speed of the leaf assembly, specifically, the movement amount and the movement speed of the individual leaf in the first direction, the movement amount in the second direction of the leaf assembly, and the movement speed according to the position and size of the previously measured tumor volume. And controls the motor accordingly.

As described above, according to the present embodiment, each leaf 311 of the leaf assembly 310 can be moved in the first direction by driving of the individual drive motor, and the leaf assembly 310 can move in the second direction Lt; / RTI > That is, in the multileaf collimator of this embodiment, the leaf can move simultaneously in the first direction and the second direction.

The radiation irradiated toward the multi-collimator is shielded by the leaf. When the leaf simultaneously moves in the first direction and the second direction, the shielded area changes. As a result, the radiation is shielded from the portion where the leaf is overlapped before and after the leaf is moved, so that the radiation is not transmitted, and the portion where the leaf is not overlapped increases in the amount of radiation to be transmitted relatively. For example, assuming that the leaf is moved by half the leaf thickness in the second direction of the leaf, if the amount of radiation delivered to the leaf area is 1, the leaf is overlapped before and after the leaf moves. And the area therebetween has a continuous radiation dose between 0 and 1.

With this principle, by moving a plurality of leaves in a second direction other than the first direction, spatial resolution in the two-dimensional direction can be remarkably improved, thereby enabling intensive radiation transmission to a desired tumor volume, So that it can be minimized.

6A and FIG. 6B that the conventional multi-leaf collimator according to the present embodiment has a remarkable effect as compared with a multi-leaf collimator in which radiation is irradiated while the leaves move in one direction.

FIGS. 6A and 6B are diagrams showing a distribution of radiation intensity and a region to which radiation is transmitted when the conventional multi-color collimator and the collimator according to the embodiment of the present invention irradiate the radiation. FIG.

6A and 6B, in FIG. 6A, the leaf of the multileaf collimator moves only in the longitudinal direction, and the region irradiated with the radiation (red display portion) is formed to be wide around the tumor volume (green display portion) On the other hand, when the leaf of the multileaf collimator is simultaneously moved in the longitudinal direction and the direction orthogonal thereto as shown in Fig. 6B, the region irradiated with the radiation (red colored portion) is concentrated around the tumor volume (green colored portion) .

That is, in the case of using the multicolor collimator according to the present embodiment, the radiation can be concentrated to the tumor volume and the exposure to the surrounding normal organ can be minimized.

On the other hand, the inventors of the present invention studied whether the same effect can be expected by stacking two multi-color collimators moving in one direction in a direction orthogonal to each other. However, in this case, it has been confirmed that not only the configuration of the entire apparatus becomes complicated but also the error of the movement of the multi-collimator moves twice as large. In addition, the excellent effect of improving the spatial resolution of the radiation distribution as in the present embodiment Respectively.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limited to the embodiments set forth herein. It can be understood that It is to be understood, therefore, that the embodiments described above are illustrative in all aspects and not restrictive.

100: source of radiation
200: first collimator
300: second collimator
311: leaf assembly
311: Leaf
320: carriage
330: Rail assembly
331: Motor
333: Guide rail
335:
400: Target

Claims

In a multi-leaf collimator comprising a pair of leaf assemblies,
Wherein the pair of leaf assemblies each have a plurality of leaves and are arranged to face each other,
Wherein a plurality of leaves of the pair of leaf assemblies are movable in a first direction in which the pair of leaf assemblies face each other and also move in a second direction perpendicular to the first direction and in which the plurality of leaves are arranged Wherein the pair of leaf assemblies facing each other are installed so as to be able to move in a second direction,
And the movement of the plurality of leaves in the second direction is in a range smaller than the thickness of the leaf measured along the second direction.

The method according to claim 1,
Wherein movement of the plurality of leaves in the first direction is achieved by driving a motor individually connected to each of the plurality of leaves.

The method according to claim 1,
Further comprising: a rail assembly including a guide rail, a motor for driving the guide rail, and a connection portion connecting the guide rail and the pair of leaf assemblies,
And movement of the plurality of leaves in the second direction is performed by operation of the guide rails.

delete

The method according to claim 1,
Wherein movement of the plurality of leaves in the second direction is performed in such a manner that a plurality of leaves respectively provided in the pair of leaf assemblies move in the same manner.